x Turn on thread page Beta
 You are Here: Home >< Maths

# Rearranging powers (Logs, I think?) watch

1. I've got the question:
The gas in a cylinder has an initial volume (V) of 0.01m^3 and a pressure (P) of 250kN/m^2. The gas is then compressed by the piston to a pressure of 800kN/m^2 according to the law P(V)^1.2 = C where C is a constant. Find the final volume giving your answer correct to five sig fig.

So I know that 250000 x 0.01^1.2 = 995.27

And so then 800000 x V^1.2 = 995.27
So V^1.2 = 0.001244

But now I'm stuck.
I tried using logs, but that just left me at a dead end. Anyone able to help with this?
2. I still don't know how to rearrange that. As I'm left with Log (base 1.2) V. I now know the answer via trial and error, but I can't rearrange the logs.
3. (Original post by IREngineerer)
I've got the question:
The gas in a cylinder has an initial volume (V) of 0.01m^3 and a pressure (P) of 250kN/m^2. The gas is then compressed by the piston to a pressure of 800kN/m^2 according to the law P(V)^1.2 = C where C is a constant. Find the final volume giving your answer correct to five sig fig.

So I know that 250000 x 0.01^1.2 = 995.27

And so then 800000 x V^1.2 = 995.27
So V^1.2 = 0.001244

But now I'm stuck.
I tried using logs, but that just left me at a dead end. Anyone able to help with this?
You could think of it like this:

V6/5 = 0.001244
V = (0.001244)5/6
4. Yes actually raise both sides to the power 5/6.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 25, 2016
Today on TSR

### Any tips for freshers...

who are introverts?

### More snow?!

Discussions on TSR

• Latest
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE